Writer and militant HIV/AIDS advocate Larry Kramer has passed away, The New York Times is reporting.

The openly gay author, playwright, and activist died Wednesday morning in New York City due to complications from pneumonia, his husband, David Webster, confirmed to The Times. Kramer was 84 and had endured multiple life-threatening illnesses throughout his lifetime, including HIV and liver disease.

A "die-in" on the lawn of the White House led by ACT UP in 1992.

Kramer was best known for his contributions to the fight against HIV/AIDS stigma during the height of the AIDS crisis in the U.S., when the disease was still largely ignored by politicians and public health officials. He founded Gay Men's Health Crisis (GMHC), America's first service organization for people living with HIV/AIDS, in 1981.

In '87, he also founded ACT UP (AIDS Coalition to Unleash Power), an activist collective known for its militant protest tactics like "die-ins." He's gone on to criticize anti-LGBTQ politicians, including President Donald Trump, in publications like The Times.

The activist was also cherished for his books and plays, including his critically acclaimed 1985 autobiographical play The Normal Heart, which dives headfirst into the horrific toll of the AIDS epidemic on the LGBTQ community. The play returned to the stage in 2011, more than 25 years after its debut. It was adapted into a movie for HBO in 2014, too.

Kramer in 1993.

Kramer's most recent work was The American People: Volume 2: The Brutality of Fact: A Novel, published this January. Less than two months ago, Kramer confirmed to The Times that he was working on a new play about the ongoing COVID-19 pandemic focusing on "gay people having to live through three plagues." The work was tentatively titled An Army of Lovers Must Not Die, but Kramer told the outlet that he'd had to change the play "almost daily as the news changes."

"I wonder if it will ever be done now," he added.

After news broke of Kramer's death, LGBTQ advocates and celebrities took to social media to pay tribute to the trailblazing AIDS activist.

Rest in power, Larry.